To investigate newer forms of immune suppression of allograft rejection and the graft-versus-host reaction (GVHR) in a rhesus monkey bone marrow transplant model prior to clinical use; to identify monkey transplantation antigens; and to establish a colony of pedigreed rhesus families to study the genetics of transplantation antigens and eventually to provide a source of related donor-recipient pairs for bone marrow transplantation. A shift in emphasis is planned from nonspecific immunosuppression involving ALS and x-ray to study a specific immunosuppression. As a basis for this in the monkey, studies during the next year will be restricted to elucidation of the RhL-A system of serologically defined antigens, of the aggregate binding inhibition system of possible "Ia" specificities, and other aspects of the genetics of the RhL-A major histocompatibility complex. Additions to the colony through selected matings within the monkey families will be continued.